Analysis of the dynamic behavior of a six-axis industrial robot within the entire workspace in respect of machining tasks

Abstract

Over the last years more and more industrial robots have been installed in almost every field of automation. Because of their high flexibility robots can be used to support tasks or to undertake complete processes. But this versatility also implicates high Cartesian compliance at the tool-center-point (TCP), due to the serial linked structure. In respect of machining tasks this compliance leads to path deviations and oscillations. Experimental modal analysis (EMA) can be used to measure the dynamic behavior of robots. Because of the large workspace this has yet only been done for a restricted area or arbitrary robot model although dedicated robot models for machining tasks are already available off the shelf. This paper presents the results of a detailed EMA within the entire workspace of a six-axis industrial robot in respect of machining tasks. In all poses, similar mode shapes were recognized. However, oscillation direction varies. Values of the eigenfrequencies show linear behavior in parts of the workspace, but some poses deviate.